LU-12066 tests: activate OSTs in recovery-small/26b

LU-12066 tests: activate OSTs in recovery-small/26b

In recovery-small.sh test_26b ensure that all OST connections are
active and not disconnected due to being idle.  Otherwise, the
number of OST exports for the remaining client may go down while
the test is running and they will never reconnect.

Change the wait condition to consider success if more exports have
disconnected than expected.

Move wait_client_evicted() down to test_26b() since it is the only
test case where this helper function is being used.

Minor test script style improvements.

Fixes: 5a6ceb664f07 ("LU-7236 ptlrpc: idle connections can disconnect")
Test-Parameters: trivial testlist=recovery-small env=ONLY=26b,ONLY_REPEAT=100
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I7b21d89ea148c4fda6527870e491f59abb3ebbe5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/56356
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>